METAL-ORGANIC RESIN DERIVED BARIUM-TITANATE .2. KINETICS OF BATIO3 FORMATION

A physicochemical model has been developed for the kinetics of barium titanate formation from X-ray-amorphous, metal organic precursors by relating the changes in the physical structure of the precursor particles with the degree of transformation in isothermally heated powder samples. From electron microscopy and gas adsorption, it is evident that the precursor particles consist of 20- to 60-nm crystallites and <10-nm intraparticle pores. A Ba,Ti oxycarbonate phase forms on heating the Ba,Ti metal organic precursor, which subsequently decomposes to form BaTiO3. It is concluded that the formation of BaTiO3 follows the shrinking core model, and the overall transformation is rate-controlled by the diffusion of CO2 through the nanometer-size intraparticle pores.